In power tools a variety of switches and electrical controls is used which may be commonly configured as non-locking keys, press keys, slide switches, toggles or the like.
The configuration and location of such switches or electrical controls cannot be chosen solely under ergonomic considerations, but must, in particular, when the housing is made from metal, follow the necessary protective regulations, whereby design and assembly of the respective power tool is complicated to a large extent.
From EP 0 126 253 A1 a screw driver has become known which utilizes a light barrier fixed to the housing which allows to sense a pot-like stop having axially extending trapezoid teeth, to thereby sense, by means of the shifting of the stop, the diameter of the tool used, to thereby control a speed regulator for the motor of the screw driver, depending on the diameter sensed.
However, this light barrier, which may also be replaced by a Hall-barrier, is coupled to an evaluation circuitry by means of an electric wire. Thus, still an electric wire connection is necessary.